Tuesday 16 September 2014 07.10 EDT
First published on Tuesday 16 September 2014 07.10 EDT

The leaders of the UK's three main political parties have signed a pledge to give more powers to Scotland if it rejects independence.

The letter, signed by David Cameron, Ed Miliband and Nick Clegg, appears on the front page of Tuesday's Daily Record newspaper. It promises "extensive new powers" for the Scottish parliament "delivered by the process and to the timetable agreed" by the three parties, and says the Scottish parliament will be made permanent.

The yes campaign said a vote for independence in Thursday's referendum was the only way to guarantee Scotland got the powers it needed.

In the joint letter, the party leaders agree that "the UK exists to ensure opportunity and security for all by sharing our resources equitably across all four nations". The letter also states: "Because of the continuation of the Barnett allocation for resources and the powers of the Scottish parliament to raise revenue, we can state categorically that the final say on how much is spent on the NHS will be a matter for the Scottish parliament."

A spokesman for Yes Scotland said: "It's clear that 'project panic' is willing to say anything in the last few days of the campaign to try to halt the yes momentum – anything except what new powers, if any, they might be willing to offer.

"The reality is that the only way to guarantee Scotland gets all the powers we need to create jobs and protect our NHS is with a Yes vote on Thursday – so that we can use our enormous wealth to create a better and fairer country."

Earlier on Monday, Gordon Brown said new powers for Scotland in the event of a no vote would unite the country. The former prime minister said there must be three guarantees: new powers to the Scottish parliament; fairness to Scotland;and the power to spend more on the NHS if that is the wish of Scottish people.

Last week Brown set out his proposed schedule for new powers to be transferred north, saying work on it would start immediately after the referendum. The Labour, Conservative and Liberal Democrat leaders in Scotland then came together to endorse the timetable for a new transfer of powers from Westminster to Holyrood.

Scotland's first minister, Alex Salmond, described last week's united front by the pro-union parties as a "retreading" and "repackaging" of earlier statements. He said at the time: "It's totally inadequate, it's not enough. It's nothing approaching the powers that Scotland needs to create jobs, to save the health service and build a better society."